During my first test drive of the evolve last weekend I was motorsailing in maybe 10 knots wind and then it made "BANG" and my mast became very loose and had a strange angle...

I was about 4 miles out with increasing offshore winds and to avoid further damage removed the mast and was really glad I had the evolve and safely made it back home...

Apparently had the same problem as viewtopic.php?f=75&t=36284meaning the screw in the hull which holds the mast receiver to the hull was broken.

Disassembled the whole mast receiver, was able to take out the broken screw and replaced it with another screw I found in my toolbox. Problem is, I could not connect the V-frame to the screw...(somehow it just didn't fit on top of the lower part of the mast receiver - even when using force).

Was really eager to go out the next day and gave up trying to connect the V-frame so I just screwed the mast collar to the hull without the V-frame...

The mast seemed to hold pretty tight and I had a great day sailing in 10 knots wind...

So now the questions is : Am I asking for major trouble sailing the TI without the V-frame connected? (...probably yes...). What is actually the function of the V-frame? (The V-frame does not seem to really "hold" the mast...).

Yes, you are definitely asking for trouble, on several fronts. the V frame helps distribute side to side forces on the mast base to the upper deck and aka braces (and to a considerably lesser extent, the fore and aft forces). Without it, all the force is on the screw connection in the fitting in the plastic of the hull. As you have seen, these parts sometimes break even when the force is distributed. Breaking the screw, as you did, debilitating as it is, offshore, is nothing compared to breaking the plastic of the hull. If you have problems with the so-called set screw holding the mast receiver base (with attached V frame) to the bottom of the boat, you should replace it with the new, stronger screw Hobie now sells (part number 88991215.). This is made of stronger stainless, and the threading is done by a different method which weakens it less; so, it is stronger. (I expect a much more sophisticated, stronger, bolt than "something you found in your toolbox" Get the real thing.) I replaced this on my boat even though the original had not failed. It also differs from the older version in that it has a slot in the top, rather than a hex recess, and is a little bit longer (I guess so the slot sticks up further and does not disappear. When you put it in, use some blue Locktite to keep it from loosening.

Then, to get the v frame to fit, you need to shorten the turnbuckle arms (measure and/or mark how long they are before you start), and then lengthen them to bring the V frame set-screw hole down over new set screw. No big force is involved. Then put the nut on the setscrew and tighten up. Even the nut has a nylon insert, looseness here is an enemy, so locktite is in order. The extra length would allow you put on a second locknut if you wanted (1/4 20 nut). I wish there were better instructions around on exactly how much the turnbuckles should be extended. Once everything is together, extending them pushes the bottom of the boat down relative to the top, and vice versa. This can affect how deeply your mast sits in the mast receiver. If too deeply, the furling pulley rubs against the receiver, and you don't want that. If not deeply enough, it probably has other bad effects I have not discovered. I just went with the length it was, but more guidance would be useful.

You are welcome. There has been quite a bit of discussion of the adjustment of the turnbuckles, but I am still wanting authoritative and clear guidance on this point.Hope your repair goes smoothly and is never needed again.